Rocker Arm help
08-19-2008, 08:55 AM
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Rocker Arm help I had a small tapping noise coming from the passenger side valve cover. You couldn't hear the tapping at idle, but while driving around 1200-1300rpm, you could hear the tapping and also the car had a hard time idling. I just installed LS7 lifters back in June '08. So I proceed to pull the valve covers and afterwards, I grab a flathead screwdriver and began to tap the rocker arms from the side. All were tight except one. It moved side to side and up and down freely. I even grabbed it with my hand and raised the rocker up and down. (it was just flapping). So then I grabbed an 8mm socket and tried to tighten it, but it was already tight. So I took the rocker arm off. I turned the motor over about an 1/8 way and put the rocker on the pedestal and bolted it down and the rocker didn't move freely anymore, it was tight. I left it like that then went inside to finish watching the Giants runs over the Browns, but fell asleep afterwards. I drove my alt. vehicle to work this morning and I was just thinking while here at work. My question is once the motor makes another 1/8th turn or a full turn, will that rocker arm have the same play in it as it did before at the same position it was loose? Or should I tighten it, then rotate then motor and see if it tightens some more?
08-19-2008, 10:23 AM
#2
It should be tight on the base circle. It was not. When you rotated it, the cam lobe pushed the lifter & push rod up & made the loose rocker tight. Rotate the motor until the valve is closed (tallest spring dimension) & tighten. Be careful not to tighten too much because the lifter has bled down & is lower than its' operating position. So, I would tighten & then back off 1/4 turn; or you can turn the engine over with the starter (injectors disconnected) for say 30 rotations & build a little lifter pressure (20-25 psi); then jump out of the car, turn the engine 'till the valve is closed, & then tighten the nut. This should get you close. Once you can't wriggle the push rod, go another 1/4 to a 1/2 turn.
08-19-2008, 10:50 AM
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It should be tight on the base circle. It was not. When you rotated it, the cam lobe pushed the lifter & push rod up & made the loose rocker tight. Rotate the motor until the valve is closed (tallest spring dimension) & tighten. Be careful not to tighten too much because the lifter has bled down & is lower than its' operating position. So, I would tighten & then back off 1/4 turn; or you can turn the engine over with the starter (injectors disconnected) for say 30 rotations & build a little lifter pressure (20-25 psi); then jump out of the car, turn the engine 'till the valve is closed, & then tighten the nut. This should get you close. Once you can't wriggle the push rod, go another 1/4 to a 1/2 turn.
08-19-2008, 11:04 AM
#4
Do you know why the one stud on the rocker arm was already tight and I couldn't go any tighter and the rocker was moving moving freely before I even took it off? Does that mean the rocker arm was loose and I should have just turned the motor and tried to tightened? the push rod was not bent and there was no visible damage to the spring...
